/*
 * Copyright � 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System.Reflection;
using Spring.Util;

namespace Spring.Objects.Support;

/// <summary>
/// Describes an event handler for an object instance.
/// </summary>
/// <author>Rick Evans</author>
public class InstanceEventHandlerValue : AbstractWiringEventHandlerValue
{
    private static readonly BindingFlags InstanceMethodFlags =
        BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic |
        BindingFlags.IgnoreCase | BindingFlags.Static;

    /// <summary>
    /// Creates a new instance of the
    /// <see cref="Spring.Objects.Support.InstanceEventHandlerValue"/> class.
    /// </summary>
    public InstanceEventHandlerValue()
    {
    }

    /// <summary>
    /// Creates a new instance of the
    /// <see cref="Spring.Objects.Support.InstanceEventHandlerValue"/> class.
    /// </summary>
    /// <param name="source">
    /// The object (possibly unresolved) that is exposing the event.
    /// </param>
    /// <param name="methodName">
    /// The name of the method on the handler that is going to handle the event.
    /// </param>
    public InstanceEventHandlerValue(object source, string methodName)
        : base(source, methodName)
    {
    }

    /// <summary>
    /// Gets the event handler.
    /// </summary>
    /// <param name="instance">
    /// The instance that is registering for the event notification.
    /// </param>
    /// <param name="info">
    /// Event metadata about the event.
    /// </param>
    /// <returns>
    /// The event handler.
    /// </returns>
    protected override Delegate GetHandler(object instance, EventInfo info)
    {
        MethodInfo methodMeta = ResolveHandlerMethod(
            ReflectionUtils.TypeOfOrType(instance),
            info.EventHandlerType,
            InstanceEventHandlerValue.InstanceMethodFlags);
        Delegate callback = null;
        if (methodMeta.IsStatic)
        {
            // case insensitive binding to a static method on an (irrelevant) instance
            callback = Delegate.CreateDelegate(
                info.EventHandlerType,
                methodMeta);
        }
        else
        {
            // case insensitive binding to an instance method on an instance
            callback =
                Delegate.CreateDelegate(
                    info.EventHandlerType,
                    instance,
                    MethodName,
                    true);
        }

        return callback;
    }
}
